This invention relates to letdown valves which are particularly useful for the letdown of slurries which are under high pressure.
In Chemical Engineering of Oct. 25, 1976, Driskell discusses the problems associated with the high-pressure letdown. In that publication he discusses a slurry letdown valve with a throttle made of a hard ceramic material, such as alumina. In his disclosure a flanged throttling body is clamped between two rings to serve as a seat for an alumina plug and to provide the throttling passage.
Hard ceramic materials can withstand compression to a good extent, but are very weak in tension. A body as disclosed by Driskell is exposed to tensile force if the throttling passage is momentarily blocked and its unsupported end could easily snap if transverse forces were applied to it.
An object of the invention is to provide a throttle for a letdown valve which is protected against tensile forces.